High activity hydrotreating catalysts

ABSTRACT

This disclosure relates to supported multi-metallic catalysts for use in the hydrotreating of hydrocarbon feeds, as well as a method for preparing such catalysts. The catalysts are prepared from a catalyst precursor comprised of at least one Group VIB metal, at least one Group VIII metal and an organic acid. The catalyst precursor is thermally treated to partially decompose the organic acid, then sulfided. The catalysts have a high carbon-as-carboxyl to total carbon ratio (C carboxy /C total ) as a result of a unique post-metal calcination method employed during the manufacture of the catalyst. As a result, the hydrotreating catalysts have lower percent weight loss-on-ignition, higher activity and longer catalyst life.

TECHNICAL FIELD

This disclosure relates to supported multi-metallic catalysts for use inthe hydrotreating of hydrocarbon feedstocks, as well as a method forpreparing such catalysts. The catalysts are prepared from a catalystprecursor comprised of at least one Group VIB metal, at least one GroupVIII metal and an organic acid. The catalyst precursor is thermallytreated to partially decompose the organic acid and then sulfided. Thecatalysts have a high carbon-as-carboxyl to total carbon ratio(C_(carboxy)/C_(total)) as a result of a unique post-metal calcinationmethod employed during the manufacture of the catalyst.

BACKGROUND

Increasing regulatory and operational pressure has resulted in the needfor hydrocarbons that have low sulfur levels and nitrogen levels.Hydrotreating processes are used by petroleum refiners to removeheteroatoms, such as sulfur and nitrogen, from hydrocarbon streams suchas naphtha, kerosene, diesel, gas oil, vacuum gas oil (VGO), and reducedcrude.

Hydrotreating is generally accomplished by contacting a hydrocarbonfeedstock in a hydrotreating reaction vessel, or zone, with a suitablehydrotreating catalyst under hydrotreating conditions of elevatedtemperature and pressure in the presence of a hydrogen-containing treatgas to yield a product having the desired level of sulfur and/ornitrogen.

Conventional hydrotreating catalysts generally contain a Group VIB metalwith one or more Group VIII metals as promoters on a refractory support,such as alumina. Hydrotreating catalysts that are particularly suitablefor hydrodesulfurization (HDS), as well as hydrodenitrogenation (HDN),generally contain molybdenum or tungsten on alumina promoted with ametal such as cobalt, nickel, iron, or a combination thereof. Cobaltpromoted molybdenum on alumina catalysts are most widely used when thelimiting specifications are hydrodesulfurization, while nickel promotedmolybdenum on alumina catalysts are the most widely used forhydrodenitrogenation, partial aromatic saturation, as well ashydrodesulfurization.

There is a continuing need for ever-more reactive and effectivecatalysts for removing heteroatoms, such as nitrogen and sulfur fromhydrocarbon streams.

SUMMARY

In one aspect, there is provided a method for preparing a catalystcomposition suitable for hydrotreating hydrocarbon feedstocks, themethod comprising: (a) impregnating an inorganic catalyst support withan aqueous solution containing (i) a salt of a Group VIB metal selectedfrom Mo and W, (ii) a salt of a Group VIII metal selected from Co andNi, and (iii) an organic acid; (b) drying the impregnated catalystsupport, thereby resulting in a metal-organic component on a driedcatalyst precursor; (c) calcining the dried catalyst precursor in anoxygen-containing atmosphere for a time and temperature sufficient tooxidize some but not all of the organic portion of the metal-organiccomponent, thereby resulting in a partially oxidized catalyst precursorhaving (i) a loss-on-ignition of greater than 1 to 20 wt. % and (ii) acarbon-as-carboxyl to total residual carbon ratio(C_(carboxy)/C_(total)) of at least 0.10 as determined by X-rayphotoelectron spectroscopy; and (d) sulfiding the partially oxidizedcatalyst precursor at sulfiding conditions in the presence of asulfiding agent, thereby resulting in a sulfided catalyst composition.

In another aspect, there is provided a catalyst composition comprising:(a) an inorganic catalyst support; and (b) a partially oxidizedmetal-organic component; wherein the catalyst composition has (i) aloss-on-ignition of greater than 1 to 20 wt. % and (ii) acarbon-as-carboxyl to total residual carbon ratio(C_(carboxy)/C_(total)) of at least 0.10 as determined by X-rayphotoelectron spectroscopy.

In yet another aspect, there is provided a process for hydrotreating ahydrocarbon feedstock, comprising: contacting the feedstock with ahydrotreating catalyst under hydrotreating conditions to produce ahydrotreated effluent, wherein the hydrotreating catalyst comprises: (a)an inorganic catalyst support; and (b) a partially oxidizedmetal-organic component; wherein the catalyst has (i) a loss-on-ignitionof greater than 1 to 20 wt. % and (ii) a carbon-as-carboxyl to totalresidual carbon ratio (C_(carboxy)/C_(total)) of at least 0.10 asdetermined by X-ray photoelectron spectroscopy.

DETAILED DESCRIPTION

The following terms will be used throughout the specification and willhave the following meanings unless otherwise indicated.

The term “hydrotreating” refers to a catalytic process, usually carriedout in the presence of free hydrogen, in which the primary purpose whenused to process hydrocarbon feedstocks is the removal of various metalcontaminants (e.g., arsenic), heteroatoms (e.g., sulfur, nitrogen andoxygen), and aromatics from the feedstock. Generally, in hydrotreatingoperations cracking of the hydrocarbon molecules (i.e., breaking thelarger hydrocarbon molecules into smaller hydrocarbon molecules) isminimized. For the purpose of this discussion, the term hydrotreatingrefers to a hydroprocessing operation in which the conversion is 20% orless, where the extent of “conversion” relates to the percentage of thefeedstock boiling above a reference temperature (e.g., 371° C.), whichis converted to products boiling below the reference temperature.

The term “organic acid” refers to a molecular entity containing at leastone carboxylic acid functional group, either in the non-ionized form(e.g., —COOH), in the ionized form (e.g., —COO⁻), or salts thereof.

The term “catalyst precursor” refers to a catalyst in unsulfided form.Use of this expression however does not exclude the fact that theunsulfided form of the catalyst also has catalytic properties.

The term “bulk dry weight” refers to the weight of a material aftercalcination at elevated temperature of over 1000° C. for 30 minutes.

As used herein, the numbering scheme for the Periodic Table Groups is asdisclosed in Chem. Eng. News, 63(5), 27 (1985).

In general, hydrotreating catalysts are composed of a support havingdeposited thereon a Group VIB metal component and a Group VIII metalcomponent. The most commonly employed Group VIB metals are molybdenumand tungsten, while cobalt and nickel are the conventional Group VIIImetals. A promoter such as phosphorus can also be present in thecatalyst.

Suitable support materials for the catalyst of the present disclosureinclude porous inorganic refractory materials such as alumina, silica,silicon carbide, amorphous and crystalline silica-aluminas,silica-magnesias, aluminophosphates, boria, titania, zirconia, and thelike, as well as mixtures and cogels thereof. Preferred supports includesilica, alumina, alumina-silica, and the crystalline silica-aluminas,particularly those materials classified as clays or zeolitic materials.More preferred support materials for purposes of this disclosure includealumina, silica, and alumina-silica, particularly either alumina orsilica.

Suitable Group VIB metals for the catalyst of the present disclosureinclude chromium (Cr), molybdenum (Mo), and tungsten (W). Preferably,the Group VIB metal is selected from Mo and W, more preferably the GroupVIB metal is Mo. The Group VIB metal component can be an oxide, an oxoacid, or an ammonium salt of an oxo or polyoxo anion. The amount of theGroup VIB metal component employed in the catalyst is generally from 5to 50 wt. % (e.g., from 10 to 40 wt. %, or from 15 to 30 wt. %), basedon the bulk dry weight of the catalyst, calculated as the metal oxide.

Suitable Group VIII metals for the catalyst of the present disclosureinclude the non-noble metals iron (Fe), cobalt (Co) and nickel (Ni) andthe noble metals palladium (Pd) and platinum (Pt). Preferably, the GroupVIII metal is a non-noble metal, more preferably the Group VIII metal isselected from Co and Ni. The Group VIII metal component is usually anoxide, hydroxide or salt, preferably a salt. The amount of the GroupVIII metal component in the catalyst of the present disclosure isgenerally from 1 to 20 wt. % (e.g., from 2 to 10 wt. %), based on thebulk dry weight of the catalyst, calculated as the metal oxide.

The total amount of metal oxide material in the catalyst of the presentdisclosure is from 1 to 50 wt. %, based on the bulk dry weight of thecatalyst. The amount of Group VIII and Group VIB metals can bedetermined via atomic absorption spectroscopy (AAS), energy dispersiveX-ray analysis (EDX), inductively coupled plasma mass spectrometry(ICP-MS) and/or X-ray fluorescence (XRF). Exemplary metal combinationsinclude Co—Mo, Co—W, Co—Ni—Mo, Co—Ni—W, Ni—Mo, Ni—W, and Ni—Mo—W.

The hydrotreating catalyst of the present disclosure can contain aphosphorus component as a promoter. The presence of phosphorus in thecatalyst can improve hydrodenitrogenation activity. When present, theamount of phosphorus compound employed in the catalyst is generally from1 to 10 wt. % (e.g., from 5 to 10 wt. %), based on the bulk dry weightof the catalyst, calculated as P₂O₅. Phosphorus can be incorporated intothe catalyst in any suitable manner by contacting the catalyst duringany one of its formative stages with an appropriate quantity of aphosphorus-containing acidic component, e.g., metaphosphoric acid,pyrophosphoric acid, phosphorous acid, orthophosphoric acid,triphosphoric acid, tetraphosphoric acid, or precursors of acids ofphosphorus, such as ammonium hydrogen phosphates (mono-ammoniumdi-hydrogen phosphate, di-ammonium mono-hydrogen phosphate, tri-ammoniumphosphate).

In general, processes for preparing conventional hydrotreating catalystsare characterized in that a support material is composited with metalcomponents, for example by impregnation, after which the composite iscalcined to convert the metal components into their oxides. Before beingused in hydrotreating, the catalysts are generally pre-sulfided toconvert the metals into their sulfides. The hydrotreating catalyst ofthe present disclosure is prepared by depositing or forming ametal-organic component in or on a support material and then partiallydecomposing the complex to produce a catalyst precursor composition. Thecatalyst precursor is converted to the resulting catalyst by sulfidingusing conventional sulfiding techniques.

The metal-organic component that is used to form the catalyst comprisesat least one organic acid and at least one catalytically active metal.The organic acid can be any organic acid that is capable of forming anorganic complex with one or more catalytically active metals. Suchorganic compounds are well known in the art of transition metalchemistry and include organic mono-dentate, bi-dentate, and poly-dentateligands. The organic acid is hypothesized to assist in producing aneffective dispersion of metals throughout the support. Hydroxycarboxylicacids are an exemplary class of organic acids. Hydroxycarboxylic acidscontain one or more carboxyl groups and one or more hydroxyl groups.Non-limiting examples of suitable hydroxycarboxylic acids includeglycolic acid, lactic acid, glyceric acid, gluconic acid, malic acid,tartaric acid, mucic acid, and citric acid. Most preferred ofhydroxycarboxylic acids are lactic acid, malic acid, tartaric acid, andcitric acid.

The organic acid and the Group VIB and Group VIII metals can be loadedonto the support by any suitable conventional technique, such asimpregnation by incipient wetness, by adsorption from excessimpregnating medium, by ion exchange, or the like, or combinationsthereof. The typical impregnation route is by incipient wetness. Theorganic acid and Group VIB and Group VIII metals can be loaded onto thesupport simultaneously or sequentially in no particular order. Theamount of the organic acid to be loaded onto the support material istypically from 0.05 to 5 molar times (e.g., from 0.1 to 4, from 0.25 to3, from 0.5 to 2, or from 0.5 to 1.5 molar times) of the number of totalnumber of moles of the metals of Group VIB and Group VIII.

The impregnated support can then be dried, e.g., by conventional dryingtechniques (for example at a temperature of about 100° C.) untilsubstantially all the water is driven off (e.g., for from 2 to 6 hours).

After deposition and/or formation of the metal-organic component in oron the support, the organic portion of the metal-organic component ispartially oxidized, or decomposed, by calcination to form a partiallyoxidized catalyst precursor having at least some residual carboncontent. By “partially oxidized” it is meant a thermal treatment processapplied to the impregnated support to bring about a partial, but notcomplete, thermal decomposition of the organic portion of themetal-organic complex. The calcination process normally takes place attemperatures below the melting point of the support, and is done underan oxygen-containing atmosphere. In an embodiment, the partialcalcination is carried out at a temperature of 350° C. to 500° C. (e.g.,from 350° C. to 450° C., from 360° C. to 500° C., or from 360° C. to500° C.) for a period of from 1 minute to 1 hour (e.g., from 5 minutesto 1 hour, from 5 to 30 minutes, or from 5 to 15 minutes). The driedimpregnated support can be calcined in, for example, a furnace such as arotary kiln, box furnace, belt dryer or the like.

One criterion for establishing that a suitable hydrotreating catalysthas been obtained is to measure the weight percent loss-on-ignition(LOI) of the partially oxidized catalyst precursor. LOI is a measure ofthe total volatiles present in the sample, essentially water and theorganic acid. The LOI test is conducted by subjecting a sample to anoxygen-containing atmosphere for 1 hour at 1020° F. (549° C.), therebyoxidizing or decomposing the organic matter or driving off all residualmoisture in the catalyst. The impregnated support is calcined to aselected loss-on-ignition (LOI) at 1020° F. (549° C.) of greater than 1to 20 wt. % (e.g., greater than 1 to 10 wt. %, greater than 1 to 9 wt.%, greater than 1 to 8 wt. %, greater than 1 to 7 wt. %, greater than 1to 6 wt. %, greater than 1 to 5 wt. %, from 2 to 20 wt. %, from 2 to 10wt. %, from 2 to 9 wt. %, from 2 to 8 wt. %, from 2 to 7 wt. %, from 2to 6 wt. %, from 2 to 5 wt. %, from 3 to 20 wt. %, from 3 to 10 wt. %,from 3 to 9 wt. %, from 3 to 8 wt. %, from 3 to 7 wt. %, from 3 to 6 wt.%, or from 3 to 5 wt. %, from 4 to 20 wt. %, from 4 to 10 wt. %, from 5to 20 wt. %, or from 5 to 10 wt. %).

Another criterion for establishing that a suitable hydrotreatingcatalyst has been obtained is to measure the ratio of carbon-as-carboxyto total residual carbon (C_(carboxy)/C_(total)) of the partiallyoxidized catalyst precursor. Enhanced HDS/HDN activity is observed whenthe C_(carboxy)/C_(total) ratio of the partially oxidized catalystprecursor is at least 0.10 (e.g., from 0.10 to 0.50, from 0.10 to 0.45,from 0.10 to 0.40, from 0.10 to 0.35, from 0.10 to 0.30, from 0.10 to0.25, at least 15, from 0.15 to 0.50, from 0.15 to 0.45, from 0.15 to0.40, from 0.15 to 0.35, or from 0.15 to 0.25). By“C_(carboxy)/C_(total) ratio” herein it is meant the ratio as determinedX-ray photoelectron spectroscopy (XPS).

The XPS data presented herein were collected by standard techniques.Powders were mounted on double-sticky tape on the sample plate forintroduction into the analysis vacuum chamber. The XPS spectra werecollected using a monochromatized Al Kα X-ray source on a PHI QuanteraXPS Scanning Microprobe. Standard charge neutralization procedures(using both low kinetic energy electrons and positive Ar ions) were usedto control charging during characterization. Data were collected atsufficiently high spectral resolution (1.0 eV resolution at a minimum)to allow deconvolution of the C 1s photoelectron peak. Standard datareduction procedures were used. The average peak position for theC_(carboxy) component is 289.4 eV, after correcting the hydrocarbon peakposition to 284.6 eV in accordance with standard XPS data handlingprocedures. C_(total) is the sum of the individual carbon-containingcomponents (e.g., hydrocarbon, alcohol/ether and carboxy).

The catalyst precursor is converted to the resulting catalyst by asulfidation step (treatment) whereby the metal components are convertedto their sulfides. In the context of the present disclosure, the phrases“sulfiding step” and “sulfidation step” are meant to include any processstep in which a sulfur-containing compound is added to the catalystcomposition and in which at least a portion of the metal componentspresent in the catalyst is converted into the sulfidic form, eitherdirectly or after an activation treatment with hydrogen. Suitablesulfidation processes are known in the art. The sulfidation step cantake place ex situ to the reactor in which the catalyst is to be used inhydrotreating hydrocarbon feeds, in situ, or in a combination of ex situand in situ to the reactor.

Ex situ sulfidation processes take place outside the reactor in whichthe catalyst is to be used in hydrotreating hydrocarbon feeds. In such aprocess, the catalyst is contacted with a sulfur compound, e.g., apolysulfide or elemental sulfur, outside the reactor and, if necessary,dried. In a second step, the material is treated with hydrogen gas atelevated temperature in the reactor, optionally in the presence of afeed, to activate the catalyst, i.e., to bring the catalyst into thesulfided state.

In situ sulfidation processes take place in the reactor in which thecatalyst is to be used in hydrotreating hydrocarbon feeds. Here, thecatalyst is contacted in the reactor at elevated temperature with ahydrogen gas stream mixed with a sulfiding agent, such as hydrogensulfide or a compound which under the prevailing conditions isdecomposable into hydrogen sulfide. It is also possible to use ahydrogen gas stream combined with a hydrocarbon feed comprising a sulfurcompound which under the prevailing conditions is decomposable intohydrogen sulfide. In the latter case, it is possible to sulfide thecatalyst by contacting it with a hydrocarbon feed comprising an addedsulfiding agent (spiked hydrocarbon feed), and it is also possible touse a sulfur-containing hydrocarbon feed without any added sulfidingagent, since the sulfur components present in the feed will be convertedinto hydrogen sulfide in the presence of the catalyst. Combinations ofthe various sulfiding techniques can also be applied. The use of aspiked hydrocarbon feed can be preferred.

The catalyst disclosed herein is employed in the conventional manner inthe form of, for example, spheres or extrudates. Examples of suitabletypes of extrudates have been disclosed in the literature (see, e.g.,U.S. Pat. No. 4,028,227). Highly suitable for use herein are cylindricalparticles (which can be hollow or not) as well as symmetrical andasymmetrical polylobed particles (2, 3 or 4 lobes).

The catalyst disclosed herein can be used in the hydrotreating of a widerange of hydrocarbon feedstocks to effect one or more ofhydrodesulfurization, hydrodenitrogenation, hydrodemetallization, andhydrodearomatization. In a hydrotreating process, a hydrocarbonfeedstream is contacted with a catalyst in a reaction zone operatedunder effective hydrotreating conditions.

The catalyst disclosed herein can be used in any one fixed-bed,fluidized-bed and moving bed reaction systems. Adoption of a fixed bed,however, is preferred from the apparatus or operation standpoint.Further, it is possible to achieve high desulfurization anddenitrogenation levels by conducting hydrotreatment in plural, that is,two or more reactors connected together.

Examples of suitable hydrocarbon feedstocks include those obtained orderived from crude petroleum oil, from tar sands, from coalliquefaction, from shale oil and from hydrocarbon synthesis, such asreduced crudes, hydrocrackates, raffinates, hydrotreated oils,atmospheric and vacuum gas oils, coker gas oils, atmospheric and vacuumresids, deasphalted oils, dewaxed oils, slack waxes, Fischer-Tropschwaxes and mixtures thereof. Suitable feedstocks range from relativelylight distillate fractions up to heavy feedstocks, such as gas oils,lube oils and resids. Non-limiting examples of light distillatefeedstocks include naphtha (typical boiling range of from 25° C. to 210°C.), diesel (typical boiling range of from 150° C. to 400° C.), keroseneor jet fuel (typical boiling range of from 150° C. to 250° C.) and thelike. Non-limiting examples of heavy feedstocks include vacuum (orheavy) gas oils (typical boiling range of from 315° C. to 610° C.),raffinates, lube oils, cycle oils, waxy oils and the like. Preferredhydrocarbon feedstocks have a boiling range of from 150° C. to 650° C.,e.g., from 150° C. to 450° C.

Hydrocarbon feedstocks suitable for treatment with the present inventioninclude, among other things, nitrogen and sulfur contaminants. Thenitrogen content of such feeds can range from 50 to 4000 ppm nitrogen(e.g., from 500 to 2000 ppm nitrogen), based on the weight of thehydrocarbon feedstock. The nitrogen can appear as both basic andnon-basic nitrogen species. Non-limiting examples of basic nitrogenspecies can include quinolines and substituted quinolines, andnon-limiting examples of non-basic nitrogen species can includecarbazoles and substituted carbazoles. The sulfur content of thehydrocarbon feedstock can range from 50 to 40,000 ppm sulfur (e.g., from5000 to 30,000 ppm sulfur), based on the weight of the hydrocarbonfeedstream. The sulfur will usually be present as organically boundsulfur compounds such as aliphatic, naphthenic, and aromatic mercaptans,sulfides, di- and polysulfides and the like. Other organically boundsulfur compounds include the class of heterocyclic sulfur compounds suchas thiophene, tetrahydrothiophene, benzothiophene and their higherhomologs and analogs. The hydrocarbon feedstocks suitable for use hereincan also contain aromatics, which are typically present in an amount offrom 10 to 60 wt. %, based on the weight of the hydrocarbon feedstock.

Exemplary hydrocarbon feedstocks suitable for treatment with the presentdisclosure are wax-containing feeds that boil in the lubricating oilrange, typically having a 10% distillation point greater than 650° F.(343° C.) and an endpoint greater than 800° F. (426° C.), as measured byASTM D86 or ASTM D2887. These hydrocarbon feedstocks can be derived frommineral sources, synthetic sources, or a mixture of the two.Non-limiting examples of suitable lubricating oil feedstocks includethose derived from sources such as oils derived from solvent refiningprocesses such as raffinates, partially solvent dewaxed oils,deasphalted oils, distillates, vacuum gas oils, coker gas oils, slackwaxes, foots oils and the like, dewaxed oils, and Fischer-Tropsch waxes.These feedstocks can also have high contents of nitrogen and sulfurcontaminants. Feedstocks containing up to about 0.25 wt. % of nitrogen,based on weight of the feed, and up to about 3.0 wt. % of sulfur, basedon the weight of the feed, can be processed in the present process.Feeds having high wax content typically have high viscosity indexes ofup to about 200 or more. Sulfur and nitrogen contents can be measured byASTM D5453 and ASTM D4629, respectively.

Representative hydrotreating conditions include a temperature of from302° F. to 752° F. (150° C. to 400° C.), e.g., from 392° F. to 752° F.(200° C. to 400° C.); a pressure of from 100 to 3000 psig (0.69 to 20.68MPa), e.g., from 200 to 2000 psig (1.38 to 13.79 MPa); a liquid hourlyspace velocity (LHSV) of from 0.1 to 10 h⁻¹, e.g., from 0.5 to 5 h⁻¹;and a hydrogen treat gas rate of from 500 to 10000 SCF/B (89 to 1780m³/m³), e.g., from 1000 to 5000 SCF/B (178 to 890 m³/m³).

The contacting of the hydrocarbon feedstock with the catalyst disclosedherein produces a hydrotreated effluent comprising at least a gaseousproduct and a hydrotreated hydrocarbon feedstock. The hydrotreatedeffluent is stripped to remove at least a portion of the gaseous productfrom the hydrotreated effluent. The means used to strip the hydrotreatedeffluent can be selected from any stripping method, process, or meansknown can be used. Non-limiting examples of suitable stripping methods,means, and processes include flash drums, fractionators, knock-outdrums, steam stripping, etc.

EXAMPLES

The following illustrative examples are intended to be non-limiting.

Example 1 Preparation of Impregnation Solution

116.7 g of citric acid was added to 400 mL of water in a round bottomflask equipped with stirrer. 194.75 g of nickel carbonate (49% Ni) wasadded to the above solution. 189.34 g of phosphoric acid (85%) was thenadded slowly to the solution and the solution was heated to 150° F.Then, 475.95 g of molybdenum trioxide was added to the solution. Thesolution was heated to about 190° F. to 210° F. and held at thattemperature range for at least 1.5 hours until the solution becameclear. Once the solution became clear, it was cooled to below 120° F.and an additional 272.8 g of citric acid was added and the mixture wasstirred until the solution became clear. The solution was diluted withdeionized water to 1000 mL. The final MoO₃ concentration was 0.4750 g/mLof solution. Analysis of the resulting solution showed the followingcomposition (metals expressed as the oxides): concentration in wt. % ona dry basis: NiO, 6.0; P₂O₅ 6.5; MoO₃, 25.0. The solution contained thefollowing component ratio: 0.4 citric acid/(NiO+MoO₃) (mol/mol).

Example 2 Preparation of Partially Oxidized Catalyst Precursors

A hydrotreating catalyst made by the unique post-metal loadingcalcination method described herein (Catalyst 1) and a hydrotreatingcatalyst made using conventional calcination techniques (Catalyst 2)were prepared.

Catalysts 1 and 2 were prepared by impregnating silica-alumina (3 wt. %SiO₂) carriers using the metal impregnation solution prepared inExample 1. The carriers were impregnated by the incipient wetnessmethod. The silica-alumina carrier had the following characteristics: asurface area 260 m²/g and a N₂ pore volume of 0.81 mL/g.

Catalysts 1 and 2 were prepared with the same metal loading but atdifferent calcination temperatures in order to achieve different LOI.

For Catalyst 1, the precursor was heated in air at 320° F. (160° C.) for10 minutes, ramped to 680° F. (360° C.) over 40 minutes, and held at680° F. for 10 minutes to achieve a LOI of 5%.

For Catalyst 2, the precursor was heated in air at 320° F. (160° C.) for10 minutes, ramped to 1000° F. (538° C.) over 40 minutes, and held at1000° F. for 10 minutes to achieve a LOI of between 0-1%.

No evidence of the presence of Ni₃C was observed in either Catalyst 1 orCatalyst 2, as determined by XPS.

The physical properties of Catalyst Precursors 1 and 2 are summarized inTable 1. The physical properties were measured after calcination at1000° F. As shown, the only significant difference between the twocatalysts is in the distribution of chemical states for carbon, whereCatalyst Precursor 1 has a higher relative concentration ofcarbon-as-carboxy.

TABLE 1 Physical Properties of Catalyst Precursors 1 and 2 CatalystCatalyst Precursor 2 Precursor 1 (Conventional) Surface Area, m²/g 148148 N₂ Pore Volume, mL/g 0.4 0.38 LOI at 1020° F. 5 1 MoO₃, wt. % 25.5126.93 NiO, wt. % 6.37 6.64 P₂O₅, wt. % 7.14 6.9 Carbon-as-Carboxy(C_(carboxy)), mol 1.37 0.33 Total Carbon (C_(total)), mol 7.11 4.08C_(carboxy)/C_(total) 0.19 0.08

Example 3 Sulfidation of Partially Oxidized Catalyst Precursors

Catalyst Precursor 1 and Catalyst Precursor 2 were each sulfided toprovide sulfided catalyst composition Catalyst 1 and Catalyst 2,respectively. The sulfiding procedures used are outlined below.

Liquid-Phase Sulfiding:

The catalyst precursor was dried in nitrogen at 150° F. and atmosphericpressure for 1 hour. The catalyst was wetted with 2.5 wt. % SULFRZOL® 54sulfiding agent (Lubrizol)/straight run (SR) diesel in hydrogen at 250°F. and 500 psig for 1 hour. Low temperature sulfiding was conducted bycontacting the catalyst with 2.5 wt. % SULFRZOL® 54/SR diesel at 480°F., 500 psig and 1 h⁻¹ LHSV for 30 hours. High temperature sulfiding wasconducted by contacting the catalyst with 2.5 wt. % SULFRZOL® 54/SRdiesel at 650° F., 2300 psig and 2⁻¹ LHSV for 8 hours. The reactortemperature was dropped to 450° F. with 2.5 wt. % SULFRZOL® 54/SR dieseland held at this temperature for 2 hours. A SR diesel line-out was heldat 680° F., 2300 psig and 2.0 h⁻¹ for 3 days. The run feed was fed intothe unit and the temperature was ramped up to unit run temperature.

Gas-Phase Sulfiding:

The catalyst precursor was dried in nitrogen at 150° F. and atmosphericpressure for 1 hour followed by drying in nitrogen at 450° F. andatmospheric pressure for 0.5 hours. Low temperature sulfiding wasconducted by contacting the catalyst with 6 wt. % dimethyl disulfide(DMDS)/heptane in hydrogen at 450° F., 500 psig and 4.0 h⁻¹ for 4 hours.High temperature sulfiding was conducted by contacting the catalyst with6 wt. % DMDS/heptane in hydrogen at 600° F., 800 psig and 4.0 h⁻¹ for 4hours. The reactor temperature was dropped to 450° F. with 6 wt. %DMDS/heptane and held at this temperature for 2 hours. A SR dieselline-out was held at 680° F., 2300 psig and 2.0 h⁻¹ for 3 days. The runfeed was fed into the unit and the temperature was ramped up to unit runtemperature.

Example 4 HDS/HDN Activity of VGO Using Catalysts 1 and 2

Catalysts 1 and 2 were employed to hydrotreat a VGO having theproperties listed in Table 2, under the process conditions listed inTable 3 below.

TABLE 2 Properties of VGO Feed API 17.2 S, wt. % 2.54 N, ppm 2484 H wt.% by NMR 11.49 Metal Content by ICP Fe, ppm 13.0 Na, ppm 2.3 Ni, ppm 1.2V, ppm 5.7 SimDist (wt. %), ° F.  0.5 472  5 628 50 820 95 988 EP 1021

TABLE 3 Hydrotreating Process Conditions Reaction Temperature, ° F. 740Total Pressure, psig 2300 H₂/Oil, SCF/B 5500 LHSV, h⁻¹ 1.0

The hydrotreating test results, expressed as relative volume amounts(RVA), using catalysts sulfided by both liquid- and gas-phase sulfiding,are outlined below in Tables 4 and 5 below, respectively.

TABLE 4 HDS/HDN Activity with Catalysts Sulfided by Liquid-PhaseSulfiding Catalyst 2 Catalyst 1 (Conventional) RVA HDN 116 97 RVA HDS117 100

TABLE 5 HDS/HDN Activity with Catalysts Sulfided by Gas-Phase SulfidingCatalyst 2 Catalyst 1 (Conventional) RVA HDN 112 97 RVA HDS 112 100

As shown in Tables 4 and 5, the HDN/HDS activity of Catalyst 1 issignificantly improved over conventional Catalyst 2.

For the purposes of this specification and appended claims, unlessotherwise indicated, all numbers expressing quantities, percentages orproportions, and other numerical values used in the specification andclaims, are to be understood as being modified in all instances by theterm “about.” Accordingly, unless indicated to the contrary, thenumerical parameters set forth in the following specification andattached claims are approximations that can vary depending upon thedesired properties sought to be obtained. It is noted that, as used inthis specification and the appended claims, the singular forms “a,”“an,” and “the,” include plural references unless expressly andunequivocally limited to one referent. As used herein, the term“include” and its grammatical variants are intended to be non-limiting,such that recitation of items in a list is not to the exclusion of otherlike items that can be substituted or added to the listed items. As usedherein, the term “comprising” means including elements or steps that areidentified following that term, but any such elements or steps are notexhaustive, and an embodiment can include other elements or steps.

Unless otherwise specified, the recitation of a genus of elements,materials or other components, from which an individual component ormixture of components can be selected, is intended to include allpossible sub-generic combinations of the listed components and mixturesthereof.

The patentable scope is defined by the claims, and can include otherexamples that occur to those skilled in the art. Such other examples areintended to be within the scope of the claims if they have structuralelements that do not differ from the literal language of the claims, orif they include equivalent structural elements with insubstantialdifferences from the literal languages of the claims. To an extent notinconsistent herewith, all citations referred to herein are herebyincorporated by reference.

1. A catalyst composition comprising: (a) an inorganic catalyst support;and (b) a partially oxidized metal-organic component; wherein thecatalyst composition has (i) a loss-on-ignition of greater than 1 to 20wt. % and (ii) a carbon-as-carboxyl to total residual carbon ratio(C_(carboxy)/C_(total)) of at least 0.10 as determined by X-rayphotoelectron spectroscopy.
 2. The catalyst composition of claim 1,further comprising a phosphorus component.
 3. The catalyst compositionof claim 2, wherein the phosphorus component is present in an amount offrom 1 to 10 wt. %, based on the bulk dry weight of the catalyst,calculated as P₂O₅.
 4. The catalyst composition of claim 1, wherein theinorganic catalyst support is selected from the group consisting ofalumina, silica, and alumina-silica.
 5. The catalyst composition ofclaim 1, wherein the metal portion of the partially oxidized metalorganic component comprises at least one Group VIB metal and at leastone Group VIII metal.
 6. The catalyst composition of claim 5, whereinthe at least one Group VIB metal is Mo and the at least one Group VIIImetal is Ni.
 7. The catalyst composition of claim 1, wherein the organicportion of the metal-organic component, prior to partial oxidation, is ahydroxycarboxylic acid.
 8. The catalyst composition of claim 7, whereinthe hydroxycarboxylic acid is selected from the group consisting ofglycolic acid, lactic acid, glyceric acid, gluconic acid, malic acid,tartaric acid, mucic acid, and citric acid.
 9. The catalyst compositionof claim 1, having a loss-on-ignition of greater than 1 to 10 wt. %. 10.The catalyst composition of claim 1, having a C_(carboxy)/C_(total)ratio of from 0.1 to 0.5.